Actuators for pressure loaded valves

ABSTRACT

Hydro-mechanical control devices for valves which are normally held in the closed position against applied fluid pressure are disclosed. The control devices include a differential area piston mechanically linked to the valve and acted upon by fluid furnished from an accumulator system. The force resulting from the application of system pressure to the small area end of the piston counterbalances the normal applied pressure thereby holding the valve closed and valve opening is achieved by placing the large area end of the piston in communication with the accumulator system.

United States Patent Legille 1 51 Aug. 8, 1972 [54] ACTUATORS FOR PRESSURE LOADED VALVES [72] Inventor: Edouard Legille, 165 rue de Treves,

Luxembourg City, Luxembourg [22] Filed: April 15,1971 21 Appl. No.2 134,358

Related US. Application Data [62] Division of Ser. No. 850,914, Aug. 18, 1969,

Pat. No. 3,601,357.

521 US. (:1. ..251/30, 251/25, 91/5 51 1m. (:1. .1 ..Fl6k 31/143, Fl5b 21/08 581 Field of Search ..251/25, 27, 26, 30; 91/47,

[56] References Cited UNITED STATES PATENTS 3,155,365 11/1964 Hartung et al ..251/25 Turner ..25l/25 X Levetus et a1 ..9 U5 X Primary Examiner-Arnold Rosenthal Attorney-Fishman & Van Kirk ABSTRACT Hydro-mechanical control devices for valves which are normally held in the closed position against applied fluid pressure are disclosed. The control devices include a differential area piston mechanically linked to the valve and acted upon by fluid furnished from an accumulator system. The force resulting from the application of system pressure to the small area end of the piston counterbalances the normal applied pressure thereby holding the valve closed and valve opening is achieved by placing the large area end of the v piston in communication with the accumulator system.

7 Claims, 2 Drawing Figures PATENTEmuc 81912 3.682.436

INVENTOR EDOUARD LEGILLE BY A ,7

ATTORNEYS ACTUATORS FOR PRESSURE LOADED VALVES CROSS REFERENCE TO RELATED APPLICATIONS This application is a division of application Ser. No. 850,914, filed Aug. 18, 1969 now 11.8. Pat. No. 3,601,357 issued Aug. 24, 1971.

BACKGROUND OF INVENTION 1 Field of the Invention The present invention relates to the actuation of valves. More specifically, the present invention relates to hydro-elastic operating devices for valves and particularly to control apparatus forbleed or pressure relief valves which are normally held closed against an applied fluid pressure. Accordingly, the general objects of the present invention are to provide novel and im-v proved methods and apparatus of such character.

2. Description of the Prior Art 7 While not limited thereto in its utility,th'e present invention is believed to be particularly well suitedfor the control of bleed or pressurerelief valves which are installed at the throat of a blast furnace. The presentinvention has also been found to be useful in the control of admission and exhaust valves for gas pressure equalizing chambers at blast furnace throats.

Prior art bleed valves of the type characterized by a mushroom-type obturator valve head which opens out-- wardly are maintained in the normally closed position by counterweights or spring assemblies; these mechanical devices compensating for the pressure of the blast furnace gases on the valve head. The closing forces imparted by the weights or springs must, of course, insure herrneticity when the valve is closed by means of exerting a closing force on the valve head which is suffipressures on the order of 1.5 kg/cm. Thespring hydraulic cylinder systems also offer an advantage in that the parts to be set in motion have very low inertia when compared with valves of the counterweight type and thus provide for rapid opening of the valves at reduced pressures. However, for the reasons to be briefly discussed below, even the most satisfactory of the prior art systems are characterized by serious deficiencies if the blast furnace on which they are installed is to be operated at an effective counterpressure of 3 or even 5 kg/cm.

Among the aforementioned deficiencies is the fact that the calibration of the closure springs in accordance with the operating pressure of the blast furnace can only be carried out locally, on the valves themselves,

under dangerous conditions. In practice, it has been i found that the spring calibration operation must be repeated whenever the working pressure of the furnace undergoes any appreciable change in order to insure that, in the case of any emergency operation such as the failure of the hydraulic equipment for the control,

ciently in excess of the counterpressure exerted by the SUMMARY OF THE INVENTION The present invention overcomes the foregoing and other deficiencies and disadvantages of the prior art by providing a bleed or pressure relief valve control mechanism which does not rely upon mechanical forces for maintaining the valve in the normally closed position. In accordance with the present invention, the function of the spring or other mechanical assemblies of the prior art is performed by the hydraulic cylinder which formerly served only to open the valve. The hydraulic cylinder is thus adapted to new conditions of operation in such a manner as to receive, on the rod or smaller area side of the piston, a pressure which is suffrsuitable operating device or by a combination of two or more of the aforementioned devices. in general, however, the prior art bleeder valve control systems were characterized by mechanical means, such as springs, for closing the valves and by hydraulic means, such as hydraulic cylinder connected to a set of hydro-elastic accumulators, for opening the valves. Thevalve opening mechanisms have typically included means whereby the opening of the valve is controlled automatically by the pressure of the blast furnace gases at the throat of the furnace. Such control means may, for example, comprise a system of adjustable pressostats which control the operation of the hydraulic cylinders to stop and start the admission of oil under pressure to the cylinder. The desired operational mode requires that the bleeder valves be opened at an intermediate pressure, the opening being achieved by overcoming the closing forces applied by the springs or other mechanical means. Opening should, of course, be at a pressure below that at which the pressostats have been preset and at which the pressure of the furnace gases will overcome the mechanical closing forces.

The above briefly described prior art bleeder valve control systems have proved satisfactory up to efl'ective ciently large to subject the valve head to the stresses which were formerly applied thereto, under the same operating conditions, by the spring or other mechanical assemblies of the prior art.

As in the prior art, the opening of the valve will be effected by the application of fluid from a pressurized source to the head or large area side of the hydraulic cylinder piston. However, in accordance with the present invention, a differential area piston is employed and the source from which pressure is applied to both sides of the piston may be the same accumulator system. Accordingly, the opening of the valve will be accomplished by means of a force unbalance which results from the application of pressurized fluid, usually from thesame source, to the opposite and different active area ends of the piston. This force unbalance will be sufficient to overcome the sum of the closing forces resulting from the hydraulic force on the smaller area (rod) side of the piston, the weight of the valve obturator, the weight of the operating lever and other mechanisms and the forces due to any auxiliary springs.

The closing of a valve opened in the manner described above is achieved merely by discharging the oil contained in the cylinder on the head (larger area) 3 side of the hydraulic cylinder piston whereby the valve will close as a result of the hydro-elastic pressure maintained on the piston at the rod side.

In accordance with a second embodiment of the invention, a hydro elastic system similar to that described above is applied to valves employed for equalizing the pressure between blast furnace top bells, i.e. to the admission and exhaust valves of a double-bell-hopper arrangement. In this arrangement of furnace top-bells, the most suitable valves presently available are also characterized by a mushroom-type obturator which is closed and maintained in the normally closed position by a spring assembly, the obturator being opened toward the outside by means of a hydraulic cylinder connected to hydro-elastic accumulators. The application of the integral hydro-elastic system in accordance with the present invention enables the spring assemblies to be eliminated and higher operating pressures to be adopted.

BRIEF DESCRIPTION OF THE DRAWING relief valve at the throat of a blast furnace; and

FIG. 2 is a schematic diagram of a second embodiment of the present invention, the valve control system of FIG. 2 being shown in the environment of a valve for equalizing the pressure between the top bells of a blast furnace.

DESCRIPTION OF THE PREFERRED EMBODIIVIENTS:

With reference now to FIG. 1, the body of a bleed or pressure relief valve, as is typically found mounted on the gas takeoff at the throat of a blast furnace, is indicated generally at l. The valve body 1 comprises a valve seat 2 and a mushroom-type obturator or valve head 3. The obturator will typically have a deflector, not shown, that will cooperate with seat 2 to seal the gas takeoff port when the valve is in the closed position as shown. a

The obturator 3 is connected, via a rod 4, to a control lever 5. Control lever 5 is pivotable about a fixed pivot point 6.

A differential area piston in hydraulic cylinder 7 is connected, via its piston rod, to control lever 5 at point 8. Hydraulic cylinder 7 is of the double-acting type and is connected on both its rod side and head side to the same system of hydro-elastic accumulators 9.-

As will be obvious to those skilled in the art, the pressure of the gas at the throat of the blast furnace will act on obturator 3 and tend to open the normally closed valve outwardly. In order to keep valve 1 closed and insure a hermetic closure, the load to which the obturator tionof pressure from the accumulator system 9 to the rod or smaller area end of the piston in cylinder 7.

In order to open the valve, the head end of cylinder 7 is placed into communication with accumulator system 9 via valve 11. This action applies the same pressure to both sides of the piston in cylinder 7. Owing to the difference between the effective areas of the two faces of the piston, oil under pressure on the rod side (small area) is forced toward the accumulator system 9 by the action of the oil at the same pressure acting on the free face (large area) of the piston. Accordingly, the piston ascends and, via the lever 5 and rod 4, raises the obturator 3.

To reclose the opened valve, the pressure on the free face of the piston is relieved by placing the head end of cylinder 7 in communication with an outlet 10 via diversion valve 11. The piston will accordingly descend, under the action of the hydro-elastic pressure maintained on the rod side thereof, and the obturator 3 is reseated.

It is to be noted that, in accordance with the present invention, instead of using a single set of hydro-elastic accumulators, the ends of the hydraulic cylinder can be connected to two separate hydro-elastic accumulator systems which exert equal or different pressures on the two faces of the piston in the cylinder.

It is also to be noted that the pressure in the accumulator system or systems can be regulated within a wide range, for example by means of a control valve 12, and such pressure regulation maybe done in complete safety in a hydraulic control room. The ability to remotely control the system provides a decided advantage in the event of an unexpected opening of the valve I; particularly when compared with prior art system wherein the spring assembly had to be regulated locally.

If necessary or desired, as shown schematically at 13, a power closing apparatus may also be employed in accordance with the present invention. If included, the power closing apparatus applies an additional force to the seal at the moment of closing of valve 1, through the application of pressure to the rod side of the piston, which is slightly in excess of that supplied by the accumulator system 9. The power closing apparatus will comprise a suitable valve system and source of hydraulic pressure.

' Similarly, an auxiliary spring 14, calibrated to the normal effective pressure of the gas at the throat, i.e. 0.2 +0.3 kglcm can be employed in order to close the valve in the event of any failure in the hydro-elastic system. An operating device based on the use of a cable winch, as shown schematically at 15, may be installed in order to effect opening operation in the event of any failure or breakdown in the hydro-elastic system.

It is also to be noted that the system as described may be controlled remotely by various means such as the use of a solenoid 16 to control diversion valve 11. Other remote and/or automatic control arrangements will be obvious to those skilled in the art.

FIG. 2 shows a second embodiment of the present invention similar to that described above; the embodiment of FIG. 2 being shown in the environment of a valve used for equalizing the pressure between the topbells at the throat of a blast furnace. In FIG. 2, the valve body 17 is mounted on the lock chamber between the top-bells of a blast furnace and, in the event of the operation of valve 17 as an admission valve, is connected to an equalization gas supply conduit. The valve body 17 is fitted with a seat 18 on which is mounted a muchroom-type obturator 19. The obturator 19 is attached to a piston rod which is in turn connected to the differential area piston in a double-acting hydraulic cylinder 7. The cylinder 7 is characterized by a pair of piston rods which extend from either end thereof. The largest effective surface area of the piston in cylinder 7 is provided by the end from which the piston rod connected to obturator 19 extends.

It is to be noted that the larger diameter rod, i.e. the rod extending from the end of the piston in cylinder 7 having the smaller effective area, has an auxiliary spring 20 associated therewith. Spring 20 is calibrated to the effective pressure which the gas assumes at the blast furnace throat in the event of the furnace operating without any counterpressure at the throat.

In order to keep the valve 17 closed and insure hermeticity during closure, an appropriate force is exerted on the obturator 19 by the piston in cylinder 7 by means of subjecting the smaller effective area side of the piston permanently to the hydro-elastic pressure furnished by accumulator system 9.

To open valve 17, the end of cylinder 7 facing the larger effective area of the piston is placed into communication with accumulator system 9 to thereby apply the same pressure to both sides of the piston. Owing to the difference between the effective areas on the two faces of the piston, application of the same pressure to both sides thereof will result in the piston ascending, as shown in FIG. 2, and the valve thereby being opened.

To reclose the opened valve, the lower end of cylinder 7 is placed in communication with an outlet 10 via a diversion valve 11. The piston will accordingly descend, under the effect of the hydro-elastic pressure maintained on the other side of the piston, and the obturator 19 will be reseated against valve seat 18.

The operation of valve 17, at the rhythm selected for the valves of the pressure equalization system between the furnace top-bells, is controlled by an automatic servocontrol system, indicated schematically at 16, in accordance with the sequence of the blast furnace chargin g program.

The above-described valve control apparatus in accordance with the present invention is applicable both to the admission valve and to the exhaust valve of the pressure equalizing system at the blast furnace throat. Thus, it may be seen that the present invention has been described by way of illustration and not limitation and various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention.

What is claimed is:

1. An actuator for a normally closed valve, said valve including a valve head and a seat and said valve head normally being subjected to forces in the opening direction, said actuator comprising:

fluid operated motion generating means, said motion generating means including a differential area piston;

means mechanically connecting the end of said motion generating means piston having the larger means mec amc y lasing sai motion generating means piston in a first direction commensurate with the closed position of the valve;

a source of pressurized fluid, the fluid source including accumulator means;

means permanently coupling the output of said accumulator means to said motion generating means whereby fluid supplied from said pressurized source will act on the smaller reaction area end of said piston means to urge the valve in said first direction; and

normally closed valve means connected between said accumulator means output and said motion generating means, said normally closed valve means having a first operative state wherein the end of said motion generating means piston connected to said connecting means may be subjected to the fluid supplied from said pressurized source thereby causing said piston to move in a second direction to open the valve, said normally closed valve means having a second operative state whereby said larger reaction area end of said piston will be isolated from said accumulator means output and the fluid acting on said larger area end of said piston will be bled off thereby permitting said valve to close under the influence of said mechanical biasing means and fluid acting on the smaller reaction area end of said piston.

2. The apparatus of claim 1 wherein said motion generating means comprises:

A double-acting cylinder having said differential area piston disposed therein, said accumulator means being directly connected to said cylinder adjacent a first end thereof and said valve means being connected to said cylinder adjacent the second end thereof.

3. The apparatus of claim 2 wherein said valve means comprises:

a solenoid operated valve.

4. The apparatus of claim 1 wherein said actuator is employed for the control of a furnace pressure control valve and wherein said mechanical connecting means comprises:

a piston rod, said piston rod coupling the head of the valve to be controlled to the larger reaction area end of the motion generating means piston.

5. The apparatus of claim 4 wherein said motion generating means comprises:

a double-acting cylinder having said differential area piston disposed therein, said accumulator means being directly connected to said cylinder adjacent a first end thereof and said valve means being connected to said cylinder adjacent the second end thereof.

6. The apparatus of claim 5 wherein said valve means comprises:

a solenoid operated valve.

7. the apparatus of claim 6 wherein said biasing means comprises:

a spring disposed in said cylinder and acting on an extension of said piston which is isolated from the system fluid. 

1. An actuator for a normally closed valve, said valve including a valve head and a seat and said valve head normally being subjected to forces in the opening direction, said actuator comprising: fluid operated motion generating means, said motion generating means including a differential area piston; means mechanically connecting the end of said motion generating means piston having the larger reaction area to said valve head; means mechanically biasing said motion generating means piston in a first direction commensurate with the closed position of the valve; a source of pressurized fluid, the fluid source including accumulator means; means permanently coupling the output of said accumulator means to said motion generating means whereby fluid supplied from said pressurized source will act on the smaller reaction area end of said piston means to urge the valve in said first direction; and normally closed valve means connected between said accumulator means output and said motion generating means, said normally closed valve means having a first operative state wherein the end of said motion generating means piston connected to said connecting means may be subjected to the fluid supplied from said pressurized source thereby causing said piston to move in a second direction to open the valve, said normally closed valve means having a second operative state whereby said larger reaction area end of said piston will be isolated from said accumulator means output and the fluid acting on said larger area end of said piston will be bled off thereby permitting said valve to close under the influence of said mechanical biasing means and fluid acting on the smaller reaction area end of said piston.
 2. The apparatus of claim 1 wherein said motion generating means comprises: A double-acting cylinder having said differential area piston disposed therein, said accumulator means being directly connected to said cylinder adjacent a first end thereof and said valve means being connected to said cylinder adjacent the second end thereof.
 3. The apparatus of claim 2 wherein said valve means comprises: a solenoid operated valve.
 4. The apparatus of claim 1 wherein said actuator is employed for the control of a furnace pressure control valve and wherein said mechanical connecting means comprises: a piston rod, said piston rod coupling the head of the valve to be controlled to the larger reaction area end of the motion generating means piston.
 5. The apparatus of claim 4 wherein said motion generating means comprises: a double-acting cylinder having said differential area piston disposed therein, said accumulator means being directly connected to said cylinder adjacent a first end thereof and said valve means being connected to said cylinder adjacent the second end thereof.
 6. The apparatus of claim 5 whereiN said valve means comprises: a solenoid operated valve.
 7. the apparatus of claim 6 wherein said biasing means comprises: a spring disposed in said cylinder and acting on an extension of said piston which is isolated from the system fluid. 